Bimetallic thermostat



Feb. 3, 1970 D. BROETTO 3,493,911

BIMETALLIC THERMOSTAT Filed Dec. 18, 1968 4A 6 3A 5A 65 N QAf 2 s s' Sel 1 I 28' 2A Se Inventor DANILO BROETTO ATTORNEYS United States Patent O 3,493,911 BIMETALLIC THERMOSTAT Danilo Broetto, Milan, Italy, assignor to Elettrotecnica VEBE S.p.A., Milan, Italy Filed Dec. 18, 1968, Ser. No. 784,815 Int. Cl. H0111 37/52 US. Cl. 337354 6 Claims ABSTRACT OF THE DISCLOSURE A bimetallic thermostat having three fixed operating temperatures. Three flexible conducting plates are arranged substantially in the form of an equilateral triangle disposed within the circular periphery of a cylindrical casing, each said plate being fixed at one end on the casing and attached to a first conductor projecting outwardly of the casing while the other end of said plate is provided with a movable contact adapted to abut a fixed contact seated on the casing and attached to a second conductor similarly projecting from the casing, each plate being insulated from the next by a rib formed in the casing, there being provided in the central region of each plate a pin slidably mounted in the casing and arranged with one in abutment with the underside of said plate, the other end being in contact with a bimetal disc peripherally supported in the casing. Reformation of the disc causes the pin and thus the plate to move to op n or close the contacts.

SUMMARY OF THE INVENTION The present invention relates to bimetallic thermostats for opening and/or closing the electric circuit of an apparatus in which a single opening and/r closing temperature of the said circuit is pre-set during assembly.

The object of the invention is to provide a bimetallic thermostat which, in a single casing of dimensions not substantially greater than required for conventional thermostats, contains three bimetallic elements adapted to actuate, at three different fixed temperatures, members arranged for the opening and/or closing of three electrical circuits to which they are respectively co-ordinated.

The foregoing and other objects of the invention will become apparent from the ensuing disclosure in which a preferred embodiment of the invention is described in detail and illustrated in the accompanying drawing. It is contemplated that minor variations in structural features and arrangement of parts thereof may occur to the skilled artisan without departing from the scope or sacrificing any of the advantages of the invention.

DESCRIPTION OF THE DRAWING FIG. 1 is a plan view of the thermostat embodying the invention.

FIG. 2 is a sectional view taken generally along 22 of FIG. 1 and in the direction indicated.

DESCRIPTION 'OF THE PREFERRED EMBODIMENT Referring to the drawings, a cylindrical casing A of electrically insulating material has afiixed thereto a star member S. Star member S includes three curved arms 7, 8 and 9 disposed at 120 relative to one another. Each "ice of the arms 7, 8 and 9 and their related parts are of substantially similar construction and therefore only one need be described in detail. At the free end of each arm 7, 8 and 9 of the star member S, the casing A has a fiat seating Se disposed parallel to the plane of the said star member S. Afiixed to each seating portion Se is a conductor 6 having a short wing 6A and a long Wing 63 disposed normal to wing 6A. The longer wing 6B of conductor 6 extends outside of casing A.

The shorter wing 6A of each conductor 6 carries a fixed contact SA. Adjacent to free end of each arm 7, 8 and 9 of star member S is a second fiat seating portion Se. Seating portions Se are separated from the seating por tions Se by an insulating rib N. The free ends of each arm 7, 8 and 9 of star member S are affixed to their adjacent seating portion Se and the end of a flexible metal conducting plate 3A is joined thereto by a suitable cou pling such as shown at 10. The free ends 12, 14 and 16 of each plate 3A are provided with a movable contact 5A arranged so as to abut the fixed contact 5'A positioned in short leg 6A of conductor 6. The fixed ends 20, 22, 24 of plates 3A are attached to the short wing 4A of an L-shaped metal conductor 4, the long wing 4B of which emerges from the casing A.

Positioned substantially at the mid-point of each plate 3A and on the underside thereof is a contact button 26 which is juxtaposed the upper end 2A of a pin 2. Pin 2 is slidable longitudinally in an axial bore 28 provided in the cylindrical casing A. The lower end 2B of the pin 2 rests at the center of a bimetal disc 1A, the edge of which is fixed in known manner to the casing A. In FIG. 2 can be seen one of the discs 1A which is concave on its upper surface, while the corresponding contact 5A, SA adjacent free end 12 is in closed position as illustrated.

When, at a predetermined temperature, the concavity of disc 1A reverses, the contact 5A, SA will open. The position of the other two contacts adjacent free ends 14 and 16 may be in the same position, that is, both closed at normal temperature and at different temperatures greater than normal, set to be opened successively. However, the desired arrangement may be such that one or more of the contacts are set to open at a normal temperature, that is, with the bimetal disc concave on its lower surface and at greater predetermined temperatures, the concavity reverses and the corresponding contact originally open, is thus arranged to close. Any desired prearranged setting for opening and closing of the contacts 5A, SA can be utilized with the attendant advantages which will be apparent to one skilled in the art.

What it is desired to claim and secure by letters Patent of the United States is:

1. A bimetallic thermostat having a plurality of fixed operating temperatures comprising, a cylindrical casing, a plurality of fiexi-ble conducting plates arranged within said casing, each said plate having a free end and a fixed end affixed to said casing, first conductors corresponding in number to said plates and affixed to said casing in contact with said fixed ends, second conductors corresponding in number to said plates and affixed to said casing adjacent said free ends, said free ends having respectively affixed thereto a movable contact abutting said second conductors, and bimetallic means abutting said plates such that upon deformation of said bimetallic means will cause 3 said free ends to move to open or close said movable con tacts.

2. A bimetallic thermostat as claimed in claim 1 in which said bimetallic means comprises a plurality of pins corresponding in number to said plates, said pins being positioned centrally of each plate, each said pin being slidably mounted in said casing with one end thereof in contact with each of said plates, and a plurality of bimetallic discs corresponding in number to said plates, each said disc being peripherally supported in said casing, the other end of each said pin being in contact with each said disc.

3. A bimetallic thermostat as claimed in claim 2 in which each said disc is adapted to deform at a different pre-set temperature.

4. A bimetallic thermostat as claimed in claim 1 in which there are three conducting plates arranged substantially in the form of an equilateral triangle.

5. A bimetallic thermostat as claimed in claim 1 inductor one to the other.

6. A bimetallic thermostat as claimed in claim 5 in which said means to connect said first conductors is a metal star-shaped member having a plurality of curved ends corresponding in number to said plates, said starshaped member having its center coincidental with the axis of said casing.

References Cited UNITED STATES PATENTS 1,894,842 1/1933 Appelberg 337-354 2,202,621 5/1940 Broune 337-35 FOREIGN PATENTS 573,135 12/ 1943 Great Britain.

G. HARRIS, Primary Examiner R. L. COHRS, Assistant Examiner US. Cl. X.R. 337-299, 335

zgz gg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No- 3 493 9ll Dated Febru ry 24. 1970 Inventor WOETTO It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

C01. 1, line 24, after one" read --end- Col; 2, line 11, read "to" as --the--.

Col 2, last line, after "means" read --by a pre-set change in temperature, said bimetallic means- SIGNED AN SEALED (SEAL) Attest:

award Ma FleIL'her, JI-

E, JR. nesting Offier I c-omissione r 0f Patents 

